眾多歐洲和拉美航班禁止使用布口罩和其它紡織品口罩 zt

Face masks have become commonplace on airplanes — and are here to stay for quite a while — but not every airline allows every kind of mask.

This week, Finnair became the latest carrier to ban fabric face masks onboard, accepting only surgical masks, valve-free FFP2 or FFP3 respirator masks, and N95 masks, the company tweeted.

"The safety of our customers and employees is our first priority. Fabric masks are slightly less efficient at protecting people from infection than surgical masks," the company wrote in a statement.

Finnair isn't alone in banning cloth face masks. Air France and Lufthansa have each mandated medical masks be worn, prohibiting fabric masks and those with exhaust valves.

LATAM Airlines has also banned fabric and reusable face masks on domestic flights within Chile, allowing only surgical masks with three layers, KN95, and N95 masks. The carrier also requires doubling up on face masks for passengers connecting in Lima, even if they remain on board the aircraft.

While cloth face masks are generally allowed in the United States, several domestic carriers have restricted other kinds of face coverings with many banning features like exhaust valves. Delta Air Lines prohibits bandanas, scarves, masks with exhaust valves, and any masks with slits, punctures, or holes. Similarly, United Airlines bans bandanas and specifies a face shield alone is not considered adequate protection.

For its part, Southwest prohibits bandanas, scarves, ski masks, balaclavas, and single layer masks; American Airlines bans balaclavas, bandanas, exhaust valves, scarves, and gaiters; JetBlue doesn't allow masks connected to tubing or battery-operated filters; and Hawaiian Airlines won't accept scarves, ski masks, balaclavas, and bandanas.

On Wednesday, the Transportation Security Administration extended a federal mask mandate until January 2022, requiring face coverings be worn on all public transportation, including on planes and in airports. The mandate was first implemented in January and was previously set to run out Sept. 13.